:root {
    /* Color Palette */
    --color-primary: #2D6A4F; /* forest green */
    --color-secondary: #74C69D; /* mint */
    --color-accent: #F4A261; /* warm orange */
    --color-accent2: #E76F51; /* coral */
    --color-background: #FEFAE0; /* cream */
    --color-text: #1B4332; /* dark green */
    --color-light-bg: #D8F3DC; /* pale green */

    /* Typography - English */
    --font-heading-en: 'Nunito', sans-serif;
    --font-body-en: 'Nunito', sans-serif; /* Single child-friendly font family */
    /* Typography - Chinese */
    --font-heading-zh: 'Noto Sans SC', sans-serif;
    --font-body-zh: 'Noto Sans SC', sans-serif;

    /* Language toggle */
    --toggle-background: #ffffff;
    --toggle-button: var(--color-primary);

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;

    /* Components */
    --border-radius: 12px;
    --shadow-sm: 0 2px 8px rgba(45, 106, 79, 0.1);
    --shadow-md: 0 4px 16px rgba(45, 106, 79, 0.15);
    --shadow-lg: 0 8px 24px rgba(45, 106, 79, 0.2);
}

/* Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-body);
    color: var(--color-text);
    background-color: var(--color-background);
    line-height: 1.6;
    font-size: 16px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Language Toggle */
.language-toggle {
    display: flex;
    background-color: var(--toggle-background);
    border: 2px solid var(--color-primary);
    border-radius: 25px;
    padding: 2px;
    cursor: pointer;
    font-family: var(--font-body-en);
    font-weight: 600;
}

.toggle-btn {
    padding: 6px 18px;
    border: none;
    background: none;
    cursor: pointer;
    border-radius: 20px;
    transition: all 0.3s ease;
    color: var(--color-text);
    font-weight: 600;
}

.toggle-btn.active {
    background-color: var(--toggle-button);
    color: white;
}

/* Typography */
h1, h2, h3, h4 {
    font-weight: 700;
    color: var(--color-primary);
    line-height: 1.2;
}

/* English Typography */
.en h1, .en h2, .en h3, .en h4 {
    font-family: var(--font-heading-en);
}

.en p, .en ul, .en li, .en a, .en button {
    font-family: var(--font-body-en);
}

/* Chinese Typography */
.zh h1, .zh h2, .zh h3, .zh h4 {
    font-family: var(--font-heading-zh);
}

.zh p, .zh ul, .zh li, .zh a, .zh button {
    font-family: var(--font-body-zh);
}

/* Language System */
/* Default to English */
body {
    font-family: var(--font-body-en);
}


/* Language toggle button styling */
#language-toggle {
    display: flex;
    align-items: center;
    gap: 8px;
    background: none;
    border: 2px solid var(--color-primary);
    border-radius: 25px;
    padding: 8px 16px;
    cursor: pointer;
    font-weight: 600;
    color: var(--color-text);
    font-size: 14px;
    transition: all 0.3s ease;
}

#language-toggle:hover {
    background-color: var(--color-primary);
    color: white;
}

#language-toggle .active-lang {
    font-weight: 700;
    color: var(--color-accent);
}

/* Content visibility - default English */
[data-lang="en"] {
    display: block;
    line-height: 1.6;
}
[data-lang="zh"] {
    display: none;
    line-height: 1.8;
}

/* Content visibility when Chinese is active */
body.lang-zh [data-lang="en"] {
    display: none;
}
body.lang-zh [data-lang="zh"] {
    display: block;
}

/* Smooth transition effects */
[data-lang] {
    transition: opacity 0.3s ease;
}

/* ========================================
   BILINGUAL SUPPORT SYSTEM
   ======================================== */

/* Language Toggle Button */
.language-toggle {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  background: rgba(255, 255, 255, 0.9);
  padding: 0.5rem 1rem;
  border-radius: 2rem;
  font-size: 0.9rem;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.language-toggle button {
  background: none;
  border: none;
  padding: 0.25rem 0.75rem;
  border-radius: 1rem;
  cursor: pointer;
  font-weight: 500;
  transition: all 0.3s ease;
  font-size: 0.9rem;
}

.language-toggle button:hover {
  background: var(--color-light-bg);
}

.language-toggle button.active {
  background: var(--color-primary);
  color: white;
}

/* Language Display Logic */
[data-lang="zh"] {
  display: none;
}

[data-lang="en"] {
  display: block;
}

body.lang-zh [data-lang="zh"] {
  display: block;
}

body.lang-zh [data-lang="en"] {
  display: none;
}

/* Chinese Typography */
body.lang-zh {
  font-family: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  line-height: 1.8;
}

body.lang-zh h1,
body.lang-zh h2,
body.lang-zh h3 {
  font-family: 'Noto Sans SC', 'PingFang SC', sans-serif;
  letter-spacing: 0.02em;
}

/* English Typography (default) */
body:not(.lang-zh) {
  font-family: 'Nunito', 'Segoe UI', sans-serif;
  line-height: 1.6;
}


h1 {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
}

h2 {
    font-size: 2rem;
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

h3 {
    font-size: 1.3rem;
    margin-bottom: var(--spacing-sm);
}

p {
    margin-bottom: var(--spacing-md);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 1rem 2rem;
    font-family: var(--font-heading);
    font-weight: 600;
    text-decoration: none;
    border-radius: var(--border-radius);
    transition: all 0.3s ease;
    font-size: 1rem;
    min-width: 180px;
    text-align: center;
}

.btn-primary {
    background-color: var(--color-primary);
    color: white;
    border: 2px solid var(--color-primary);
}

.btn-primary:hover {
    background-color: #23523d;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: var(--color-accent);
    color: white;
    border: 2px solid var(--color-accent);
}

.btn-secondary:hover {
    background-color: #e08f4a;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

/* Header */
.header {
    background-color: white;
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) 0;
}

.logo {
    font-family: var(--font-heading);
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--color-primary);
}

/* Navigation */
.nav-desktop {
    display: flex;
    gap: var(--spacing-lg);
}

.nav-desktop a {
    font-family: var(--font-heading);
    font-weight: 600;
    color: var(--color-primary);
    text-decoration: none;
    transition: color 0.3s ease;
    font-size: 1.1rem;
}

.nav-desktop a:hover {
    color: var(--color-accent);
}

.hamburger {
    display: none;
    background: none;
    border: none;
    font-size: 2rem;
    cursor: pointer;
    color: var(--color-primary);
}

.nav-mobile {
    display: none;
}

/* Hero Section */
.hero {
    padding: var(--spacing-xl) 0;
    background-color: var(--color-light-bg);
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    align-items: center;
}

.hero-subhead {
    font-size: 1.3rem;
    margin-bottom: var(--spacing-lg);
    color: #3a5a40;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.hero-visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.illustration-placeholder {
    background-color: rgba(255, 255, 255, 0.8);
    padding: var(--spacing-xl);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    font-size: 4rem;
    text-align: center;
    color: var(--color-primary);
}

/* Philosophy Banner */
.philosophy-banner {
    padding: var(--spacing-lg);
    background-color: var(--color-primary);
    color: white;
}

.philosophy-banner p {
    margin: 0;
    text-align: center;
    font-size: 1.1rem;
    font-style: italic;
    font-weight: 300;
}

/* Card Grid */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
}

.card {
    background-color: white;
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
    text-decoration: none;
    color: var(--color-text);
    cursor: pointer;
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.card-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
}

.card-subtitle {
    font-weight: 600;
    color: var(--color-accent);
    margin-bottom: var(--spacing-sm);
}

/* Age Stages */
.age-stages {
    padding: var(--spacing-xl) 0;
}

/* Learning Areas */
.learning-areas {
    padding: var(--spacing-xl) 0;
    background-color: var(--color-light-bg);
}

/* Daily Life Section */
.daily-life {
    padding: var(--spacing-xl) 0;
    text-align: center;
}

.daily-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.daily-item {
    background-color: var(--color-accent);
    color: white;
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
    font-family: var(--font-heading);
    font-weight: 600;
    font-size: 1.2rem;
    box-shadow: var(--shadow-md);
}

.daily-note {
    font-style: italic;
    color: #52b788;
}

/* Quote Section */
.quote-section {
    padding: var(--spacing-xl) 0;
    background-color: var(--color-light-bg);
}

.research-quote {
    max-width: 700px;
    margin: 0 auto;
    padding: var(--spacing-xl);
    background-color: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
}

.research-quote::before {
    content: "“";
    font-size: 4rem;
    color: var(--color-secondary);
    position: absolute;
    margin-left: -2rem;
    margin-top: -1rem;
}

.research-quote::after {
    content: "”";
    font-size: 4rem;
    color: var(--color-secondary);
    position: relative;
    top: 1rem;
}

.research-quote footer {
    text-align: right;
    margin-top: var(--spacing-md);
    color: var(--color-accent);
    font-weight: 600;
}

/* Footer */
.footer {
    background-color: var(--color-primary);
    color: white;
    padding: var(--spacing-xl) 0;
    margin-top: var(--spacing-xl);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.footer-column h4 {
    color: var(--color-accent);
    margin-bottom: var(--spacing-md);
}

.footer-column a {
    display: block;
    color: white;
    text-decoration: none;
    margin-bottom: var(--spacing-sm);
    transition: color 0.3s ease;
}

.footer-column a:hover {
    color: var(--color-accent);
}

.footer-info {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: var(--spacing-md);
    text-align: center;
    font-size: 0.9rem;
}

.footer-info p {
    margin-bottom: var(--spacing-sm);
    opacity: 0.9;
}

/* Mobile Responsive */
@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }

    h2 {
        font-size: 1.6rem;
    }

    .nav-desktop {
        display: none;
    }

    .hamburger {
        display: block;
    }

    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-buttons {
        justify-content: center;
    }

    .illustration-placeholder {
        font-size: 3rem;
        padding: var(--spacing-lg);
    }

    .card-grid {
        grid-template-columns: 1fr;
    }

    .daily-grid {
        grid-template-columns: 1fr;
    }

    .research-quote {
        padding: var(--spacing-md);
    }

    .research-quote::before,
    .research-quote::after {
        font-size: 2rem;
    }
}

@media (max-width: 480px) {
    .btn {
        padding: 0.8rem 1.5rem;
        font-size: 0.9rem;
        min-width: 150px;
    }

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
}


/* Page Content Styles */
.page-content {
    padding: var(--spacing-xl) 0;
}

.page-content h1 {
    text-align: center;
    margin-bottom: var(--spacing-md);
}

.page-content .card {
    margin-bottom: var(--spacing-md);
}

/* Book Card Styles */
.book-card {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-md);
}

/* Myth-Fact Card Styles */
.myth {
    color: var(--color-accent2); /* Coral for myths */
    margin-bottom: var(--spacing-md);
}

.fact {
    color: var(--color-primary); /* Forest green for facts */
    margin-bottom: var(--spacing-md);
}

.explanation-box {
    background-color: var(--color-light-bg);
    padding: var(--spacing-md);
    border-radius: var(--border-radius);
    margin-top: var(--spacing-sm);
    font-size: 0.9rem;
    font-style: italic;
}

.book-cover-placeholder {
    font-size: 4rem;
}

/* Behavior Explanation Cards */
.behavior-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.behavior-card {
  background: white;
  border-radius: 1rem;
  padding: 1.5rem;
  box-shadow: 0 4px 15px rgba(0,0,0,0.08);
}

.behavior-question {
  color: var(--color-accent2);
  font-weight: 600;
  margin-bottom: 0.75rem;
  font-size: 1.1rem;
}

.behavior-answer {
  color: #555;
  line-height: 1.6;
}

/* Checklist Styles */
.checklist-container {
  background: white;
  border-radius: 1rem;
  padding: 2rem;
  box-shadow: 0 4px 15px rgba(0,0,0,0.08);
  margin: 2rem 0;
}

.checklist-item {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  padding: 0.75rem 0;
  border-bottom: 1px solid #eee;
}

.checklist-item:last-child {
  border-bottom: none;
}

.checklist-checkbox {
  width: 1.5rem;
  height: 1.5rem;
  border: 2px solid var(--color-primary);
  border-radius: 0.25rem;
  flex-shrink: 0;
  margin-top: 0.1rem;
}

/* Sources Footer */
.sources-section {
  background: #f8f9fa;
  padding: 2rem;
  border-radius: 1rem;
  margin-top: 3rem;
}

.sources-section h3 {
  color: var(--color-accent);
  margin-bottom: 1rem;
}

.source-item {
  margin-bottom: 0.75rem;
  padding-left: 1rem;
  border-left: 2px solid var(--color-secondary);
  font-size: 0.9rem;
  color: #555;
}

/* Parent Support Section */
.parent-support-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.support-card {
  background: linear-gradient(135deg, #fff 0%, var(--color-light-bg) 100%);
  border-radius: 1rem;
  padding: 1.5rem;
  box-shadow: 0 4px 15px rgba(0,0,0,0.08);
}

.support-card h3 {
  color: var(--color-secondary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Page Hero for Content Pages */
.content-hero {
  background: linear-gradient(135deg, var(--color-light-bg) 0%, #fff5e6 100%);
  padding: 4rem 2rem;
  text-align: center;
  margin-bottom: 3rem;
}

.content-hero h1 {
  color: var(--color-primary);
  margin-bottom: 1rem;
}

.content-hero .subtitle {
  font-size: 1.2rem;
  color: #666;
  max-width: 600px;
  margin: 0 auto;
}

/* Navigation Tabs */
.content-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 2px solid #eee;
}

.tab-btn {
  padding: 0.75rem 1.5rem;
  border: none;
  background: #f0f0f0;
  border-radius: 2rem;
  cursor: pointer;
  font-weight: 500;
  transition: all 0.3s ease;
}

.tab-btn:hover {
  background: var(--color-light-bg);
}

.tab-btn.active {
  background: var(--color-primary);
  color: white;
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

.book-info {
    flex: 1;
}

/* Activity Styles */
.activity {
    margin-bottom: var(--spacing-lg);
}

.activity h4 {
    margin-bottom: var(--spacing-sm);
    color: var(--color-accent);
}

.parent-tip, .research-note, .safety-note {
    background-color: var(--color-light-bg);
    padding: var(--spacing-md);
    border-radius: var(--border-radius);
    margin-top: var(--spacing-sm);
    font-size: 0.95rem;
}

.parent-tip strong, .research-note strong, .safety-note strong {
    color: var(--color-primary);
}